2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section[CodeGen]{@CodeGen@: main module of the code generator}
6 This module says how things get going at the top level.
8 @codeGen@ is the interface to the outside world. The \tr{cgTop*}
9 functions drive the mangling of top-level bindings.
11 %************************************************************************
13 \subsection[codeGen-outside-interface]{The code generator's offering to the world}
15 %************************************************************************
18 module CodeGen ( codeGen ) where
20 #include "HsVersions.h"
22 -- Kludge (??) so that CgExpr is reached via at least one non-SOURCE
23 -- import. Before, that wasn't the case, and CM therefore didn't
24 -- bother to compile it.
25 import CgExpr ( {-NOTHING!-} ) -- DO NOT DELETE THIS IMPORT
28 import CgBindery ( CgIdInfo, addBindC, addBindsC, getCgIdInfo,
30 import CgClosure ( cgTopRhsClosure )
31 import CgCon ( cgTopRhsCon, cgTyCon )
32 import CgUtils ( cmmRegOffW, emitRODataLits, cmmNeWord )
36 import CmmUtils ( zeroCLit, mkIntCLit, mkLblExpr )
37 import PprCmm ( pprCmms )
38 import MachOp ( wordRep )
41 import PrelNames ( gHC_PRIM, rOOT_MAIN, gHC_TOP_HANDLER )
42 import DynFlags ( DynFlags(..), DynFlag(..), dopt )
43 import StaticFlags ( opt_SccProfilingOn )
45 import PackageConfig ( PackageId )
46 import HscTypes ( ForeignStubs(..) )
47 import CostCentre ( CollectedCCs )
48 import Id ( Id, idName, setIdName )
49 import Name ( nameSrcLoc, nameOccName, nameUnique, isInternalName, mkExternalName )
50 import OccName ( mkLocalOcc )
51 import TyCon ( TyCon )
52 import Module ( Module )
53 import ErrUtils ( dumpIfSet_dyn, showPass )
56 import Panic ( assertPanic )
65 -> [Module] -- directly-imported modules
66 -> CollectedCCs -- (Local/global) cost-centres needing declaring/registering.
67 -> [(StgBinding,[(Id,[Id])])] -- Bindings to convert, with SRTs
70 codeGen dflags this_mod data_tycons foreign_stubs imported_mods
71 cost_centre_info stg_binds
73 { showPass dflags "CodeGen"
74 ; let way = buildTag dflags
75 main_mod = mainModIs dflags
78 -- ; mapM_ (\x -> seq x (return ())) data_tycons
80 ; code_stuff <- initC dflags this_mod $ do
81 { cmm_binds <- mapM (getCmm . cgTopBinding dflags) stg_binds
82 ; cmm_tycons <- mapM cgTyCon data_tycons
83 ; cmm_init <- getCmm (mkModuleInit dflags way cost_centre_info
85 foreign_stubs imported_mods)
86 ; return (cmm_binds ++ concat cmm_tycons ++ [cmm_init])
88 -- Put datatype_stuff after code_stuff, because the
89 -- datatype closure table (for enumeration types) to
90 -- (say) PrelBase_True_closure, which is defined in
93 ; dumpIfSet_dyn dflags Opt_D_dump_cmm "Cmm" (pprCmms code_stuff)
98 %************************************************************************
100 \subsection[codegen-init]{Module initialisation code}
102 %************************************************************************
104 /* -----------------------------------------------------------------------------
105 Module initialisation
107 The module initialisation code looks like this, roughly:
110 JMP_(__stginit_Foo_1_p)
113 FN(__stginit_Foo_1_p) {
117 We have one version of the init code with a module version and the
118 'way' attached to it. The version number helps to catch cases
119 where modules are not compiled in dependency order before being
120 linked: if a module has been compiled since any modules which depend on
121 it, then the latter modules will refer to a different version in their
122 init blocks and a link error will ensue.
124 The 'way' suffix helps to catch cases where modules compiled in different
125 ways are linked together (eg. profiled and non-profiled).
127 We provide a plain, unadorned, version of the module init code
128 which just jumps to the version with the label and way attached. The
129 reason for this is that when using foreign exports, the caller of
130 startupHaskell() must supply the name of the init function for the "top"
131 module in the program, and we don't want to require that this name
132 has the version and way info appended to it.
133 -------------------------------------------------------------------------- */
135 We initialise the module tree by keeping a work-stack,
137 * that grows downward
138 * Sp points to the last occupied slot
144 -> String -- the "way"
145 -> CollectedCCs -- cost centre info
147 -> Module -- name of the Main module
151 mkModuleInit dflags way cost_centre_info this_mod main_mod foreign_stubs imported_mods
153 if opt_SccProfilingOn
154 then do { -- Allocate the static boolean that records if this
155 -- module has been registered already
156 emitData Data [CmmDataLabel moduleRegdLabel,
157 CmmStaticLit zeroCLit]
159 ; emitSimpleProc real_init_lbl $ do
160 { ret_blk <- forkLabelledCode ret_code
162 ; init_blk <- forkLabelledCode $ do
163 { mod_init_code; stmtC (CmmBranch ret_blk) }
165 ; stmtC (CmmCondBranch (cmmNeWord (CmmLit zeroCLit) mod_reg_val)
167 ; stmtC (CmmBranch init_blk)
170 else emitSimpleProc real_init_lbl ret_code
172 -- Make the "plain" procedure jump to the "real" init procedure
173 ; emitSimpleProc plain_init_lbl jump_to_init
175 -- When compiling the module in which the 'main' function lives,
176 -- (that is, this_mod == main_mod)
177 -- we inject an extra stg_init procedure for stg_init_ZCMain, for the
178 -- RTS to invoke. We must consult the -main-is flag in case the
179 -- user specified a different function to Main.main
180 ; whenC (this_mod == main_mod)
181 (emitSimpleProc plain_main_init_lbl jump_to_init)
184 this_pkg = thisPackage dflags
186 plain_init_lbl = mkPlainModuleInitLabel this_pkg this_mod
187 real_init_lbl = mkModuleInitLabel this_pkg this_mod way
188 plain_main_init_lbl = mkPlainModuleInitLabel this_pkg rOOT_MAIN
190 jump_to_init = stmtC (CmmJump (mkLblExpr real_init_lbl) [])
192 mod_reg_val = CmmLoad (mkLblExpr moduleRegdLabel) wordRep
194 -- Main refers to GHC.TopHandler.runIO, so make sure we call the
195 -- init function for GHC.TopHandler.
197 | this_mod == main_mod = [gHC_TOP_HANDLER]
201 { -- Set mod_reg to 1 to record that we've been here
202 stmtC (CmmStore (mkLblExpr moduleRegdLabel) (CmmLit (mkIntCLit 1)))
204 -- Now do local stuff
205 ; initCostCentres cost_centre_info
206 ; mapCs (registerModuleImport this_pkg way)
207 (imported_mods++extra_imported_mods)
210 -- The return-code pops the work stack by
211 -- incrementing Sp, and then jumpd to the popped item
212 ret_code = stmtsC [ CmmAssign spReg (cmmRegOffW spReg 1)
213 , CmmJump (CmmLoad (cmmRegOffW spReg (-1)) wordRep) [] ]
215 -----------------------
216 registerModuleImport :: PackageId -> String -> Module -> Code
217 registerModuleImport this_pkg way mod
220 | otherwise -- Push the init procedure onto the work stack
221 = stmtsC [ CmmAssign spReg (cmmRegOffW spReg (-1))
222 , CmmStore (CmmReg spReg) (mkLblExpr (mkModuleInitLabel this_pkg mod way)) ]
227 Cost-centre profiling: Besides the usual stuff, we must produce
228 declarations for the cost-centres defined in this module;
230 (The local cost-centres involved in this are passed into the
234 initCostCentres :: CollectedCCs -> Code
235 -- Emit the declarations, and return code to register them
236 initCostCentres (local_CCs, ___extern_CCs, singleton_CCSs)
237 | not opt_SccProfilingOn = nopC
239 = do { mapM_ emitCostCentreDecl local_CCs
240 ; mapM_ emitCostCentreStackDecl singleton_CCSs
241 ; mapM_ emitRegisterCC local_CCs
242 ; mapM_ emitRegisterCCS singleton_CCSs
246 %************************************************************************
248 \subsection[codegen-top-bindings]{Converting top-level STG bindings}
250 %************************************************************************
252 @cgTopBinding@ is only used for top-level bindings, since they need
253 to be allocated statically (not in the heap) and need to be labelled.
254 No unboxed bindings can happen at top level.
256 In the code below, the static bindings are accumulated in the
257 @MkCgState@, and transferred into the ``statics'' slot by @forkStatics@.
258 This is so that we can write the top level processing in a compositional
259 style, with the increasing static environment being plumbed as a state
263 cgTopBinding :: DynFlags -> (StgBinding,[(Id,[Id])]) -> Code
264 cgTopBinding dflags (StgNonRec id rhs, srts)
265 = do { id' <- maybeExternaliseId dflags id
266 ; mapM_ (mkSRT (thisPackage dflags) [id']) srts
267 ; (id,info) <- cgTopRhs id' rhs
268 ; addBindC id info -- Add the *un-externalised* Id to the envt,
269 -- so we find it when we look up occurrences
272 cgTopBinding dflags (StgRec pairs, srts)
273 = do { let (bndrs, rhss) = unzip pairs
274 ; bndrs' <- mapFCs (maybeExternaliseId dflags) bndrs
275 ; let pairs' = zip bndrs' rhss
276 ; mapM_ (mkSRT (thisPackage dflags) bndrs') srts
277 ; _new_binds <- fixC (\ new_binds -> do
278 { addBindsC new_binds
279 ; mapFCs ( \ (b,e) -> cgTopRhs b e ) pairs' })
282 mkSRT :: PackageId -> [Id] -> (Id,[Id]) -> Code
283 mkSRT this_pkg these (id,[]) = nopC
284 mkSRT this_pkg these (id,ids)
285 = do { ids <- mapFCs remap ids
287 ; emitRODataLits (mkSRTLabel (idName id))
288 (map (CmmLabel . mkClosureLabel this_pkg . idName) ids)
291 -- Sigh, better map all the ids against the environment in
292 -- case they've been externalised (see maybeExternaliseId below).
293 remap id = case filter (==id) these of
294 (id':_) -> returnFC id'
295 [] -> do { info <- getCgIdInfo id; return (cgIdInfoId info) }
297 -- Urgh! I tried moving the forkStatics call from the rhss of cgTopRhs
298 -- to enclose the listFCs in cgTopBinding, but that tickled the
299 -- statics "error" call in initC. I DON'T UNDERSTAND WHY!
301 cgTopRhs :: Id -> StgRhs -> FCode (Id, CgIdInfo)
302 -- The Id is passed along for setting up a binding...
303 -- It's already been externalised if necessary
305 cgTopRhs bndr (StgRhsCon cc con args)
306 = forkStatics (cgTopRhsCon bndr con args)
308 cgTopRhs bndr (StgRhsClosure cc bi fvs upd_flag srt args body)
309 = ASSERT(null fvs) -- There should be no free variables
310 setSRTLabel (mkSRTLabel (idName bndr)) $
311 forkStatics (cgTopRhsClosure bndr cc bi srt upd_flag args body)
315 %************************************************************************
317 \subsection{Stuff to support splitting}
319 %************************************************************************
321 If we're splitting the object, we need to externalise all the top-level names
322 (and then make sure we only use the externalised one in any C label we use
323 which refers to this name).
326 maybeExternaliseId :: DynFlags -> Id -> FCode Id
327 maybeExternaliseId dflags id
328 | dopt Opt_SplitObjs dflags, -- Externalise the name for -split-objs
329 isInternalName name = do { mod <- moduleName
330 ; returnFC (setIdName id (externalise mod)) }
331 | otherwise = returnFC id
333 externalise mod = mkExternalName uniq mod new_occ Nothing loc
335 uniq = nameUnique name
336 new_occ = mkLocalOcc uniq (nameOccName name)
337 loc = nameSrcLoc name
338 -- We want to conjure up a name that can't clash with any
339 -- existing name. So we generate
341 -- where 243 is the unique.